Storing, Accessing, and Displaying JSON Data in Local Storage


Introduction

In modern web development, storing data locally in a user’s browser is a powerful way to create dynamic and user-friendly applications. Whether you’re saving user preferences, caching data for offline use, or managing application state, local storage is a key tool in your toolkit. Combined with JSON (JavaScript Object Notation), a lightweight data format, you can easily store and retrieve structured data.

In this tutorial, you’ll learn how to do the following:

  • Store JSON data in local storage.
  • Retrieve and parse JSON data from local storage.
  • Display the data dynamically on a webpage.
I'm sure that by the end of this guide, you’ll have a solid understanding of how to use these technologies together to enhance your web applications.

Now let's get right into it!

Tutorial

Step 1: We First Need to Understanding JSON and Local Storage
Before diving into the code, let’s briefly understand the two key technologies we’ll be using:

1. JSON (JavaScript Object Notation)

JSON is a lightweight data format that uses key-value pairs to represent data. It’s easy for humans to read and write, and it’s easy for machines to parse and generate. Now here’s an example of a JSON object:









2. Local Storage: What is it really?

Local storage is a web API that allows you to store data persistently in a user’s browser. Unlike session storage, which clears data when the browser is closed, local storage retains data even after the browser is closed and reopened. Local storage can only store strings, so we’ll need to convert JSON objects into strings before storing them.

Step 2: Storing the JSON Data in Local Storage

Now to store JSON data in local storage, we first need to convert the JSON object into a string using JSON.stringify(). Here’s how we can do that:








In the example above:

  • We create a JSON object called user.
  • We convert the object to a string using JSON.stringify().
  • We store the string in local storage using localStorage.setItem().


Step 3: Accessing JSON Data from Local Storage

To retrieve the JSON data from local storage, we use localStorage.getItem() and then convert the string back into a JSON object using JSON.parse(). We can do this by:








Here:

  • We retrieve the string from local storage using localStorage.getItem().
  • We convert the string back into a JSON object using JSON.parse().
  • We access the data using dot notation (e.g., user.name).

Step 4: Displaying JSON Data on a Webpage

Now that we’ve retrieved the JSON data, let’s display it dynamically on a webpage. Here’s how we do this:









Here:

  • We create a <div> with the ID user-info to hold the JSON data.
  • We retrieve the JSON data from local storage and parse it.
  • We use JavaScript to dynamically insert the data into the HTML using template literals.

Step 5: Managing Data Lifetime and Scope

Local storage data persists across browser sessions, but you may want to clear it under certain conditions. Here’s how we to manage local storage data:

1. Clear a Specific Item:   localStorage.removeItem("userData");

2. Clear All Data:  localStorage.clear();

3. Set an Expiration Date:

Local storage doesn’t have built-in expiration, but you can implement it manually by storing a timestamp alongside your data:








Take a look at these helpful Additional Resources:

 These can really help to deepen your understanding of JSON and local storage

MDN Web Docs: Local Storage
https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage

JSON.org
https://www.json.org/json-en.html

W3Schools: JavaScript Local Storage
https://www.w3schools.com/js/js_json.asp

JavaScript.info: Local Storage
https://javascript.info/localstorage




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